This project will further characterize the potassium transport systems of Escherichia coli. This is a very good model system for the study of potassium transport, since biochemical, physiological, and genetic methods can be used. There are many similarities between animal cell mitochondria and gram-negative bacteria such as E. coli, suggesting that information about potassium uptake in the bacteria can be used to explore the corresponding process in mitochondria. Specific goals of this work are: 1) to define the energy coupling for potassium transport, 2) to identify, isolate, and characterize protein components of the bacterial potassium transport systems, and 3) to gain more complete understanding by the isolation of a new class of mutants defective in potassium transport.